Viscose composition and method of spinning



U s atement VISCOSE COMPOSITICN AND METHOD OF SPINNING can ViscoseCorporation, Philadelphia, Pa, :1 corporation of Delaware No Drawing.Application September 21, 1953, Serial No. 381,463

17 Claims. (Cl. 1854) This invention relates to the production of shapedbodies of regenerated cellulose from viscose. 1

In the conventional method of producing shaped bodies of regeneratedcellulose from viscose, a suitable cellulosic material such as purifiedcotton linters, wood pulp, mixtures thereof, and the like is firstconverted to an alkali cellulose by treatment with a caustic sodasolution and after shredding the treated cellulose material, itisallowed to age. The aged alkali cellulose is then converted to axanthate by treatment with carbon disulfide. The cellulose xanthate issubsequently dissolved in a caustic soda solution in an amountcalculated to provide a viscose of the desired cellulose and alkalicontent. After filtration, the viscose solution is allowed to ripen andis subsequently extruded through a shaped orifice into a suitablecoagulating and regenerating bath.

In the production of filaments, the viscose solution .is extrudedthrough a spinneret into a coagulating and regenerating bath consistingof an aqueous acid solution containing zinc sulfate. The filament maysubsequently be passed through a hot aqueous bath Where it is stretchedto improve its properties such as tensile strength. The filament maythen be passed through a dilute aqueous solution of sulfuric acid andsodium. sulfate to complete the regeneration of the cellulose, in caseit is not completely regenerated upon leaving the stretching stage. Thefilament is subsequently subjected to washing, purification, bleaching,possibly other treating operations and drying, being collected eitherbefore or after these treatments.

The filaments as formed by the conventional methods, consist of a skinor outer shell portion and a core portion with a sharp line ofdemarcation'between the two. The cross-section of the filaments exhibitsa very irregular .or crenulated exterior surface. The skin and coreportions of the filament represent differences in crystalstmcture andthe different portions possess different swelling and stainingcharacteristics. The sharply irregular and crenulated surface structurehas a relatively low abrasion resistance and readily picks up foreignparticles such as dirt.

It has now been discovered that the incorporation of small amounts ofhexamethylenetetramine in viscose results in the production ofregenerated cellulosic shaped bodies such as filaments, films, sheetsand the like having improved properties and characterisitcs. The mostreadily distinguishable characteristics as compared to conventionalfilaments include a smooth, non-crenulated surface and the filamentsconsist entirely of skin.

The hexamethylenetetramine may be .added at .any desired stage in theproduction of the viscose, preferably being added after the cellulosexanthate has been dissolved in the caustic solution. The amount ofhexamethylenetetramine added to and incorporated in the viscose shouldbe at least about 0.1 mole per 100 kgs. of viscose and may vary over'awide range, namely,:from about 0.1 to about and even up to 20 or moremoles per 100 kgs. of viscose. I prefer to incorporate in the stantiallyentirely of skin.

throughout the filament.

2,792,278 Patented May 14, 1957 viscose an amount of from about 0.2 toabout 5 moles per 100 kgs. of viscose.

Amounts Within the preferred range are effective, however, lesser orgreater amounts do not adversely affect the properties andcharacteristics of the products.

Regenerated cellulose filaments prepared from viscose containing thesmall amounts of hexamethylenetetramine have a smooth or non-crenulatedsurface and consist sub- Because of the uniformity of crystal structurethroughout the filament, the swelling and staining characteristics areuniform throughout the cross-section of the filament. Filaments producedpursuant to this invention and consisting entirely of skin have a hightoughness and a greater flexing life which may be attributed .by theuniformity in skin structure Although the twisting of con- --ventionalfilaments, as in the production of tire cord, re-

from the filaments consisting entirely of skin.

and churning for about 2 /2 hours.

per minute.

sults inan appreciable loss of tensile strength, there is little loss intensile strength in the production of cords Fila 'ments prepared fromviscose containing hexamethylenetetramine have a high tensile strengthas compared to normal regenerated cellulose filaments and have superiorabrasion and fatigue resistance characteristics. Such filaments arehighly satisfactory for the production of cords for the reinforcement ofrubber products such as pneumatic tire casings, but the filaments arenot restricted to such uses and may be used for other textileapplications.

.The invention may be illustrated by reference to the preparation ofregenerated cellulose filaments from a viscose containing 7% cellulose,6% caustic soda, and

having a total carbon disulfide content of about 41%. The viscosesolutions were prepared by xanthating alkali cellulose by theintroduction of 36% carbon disulfide The cellulose xanthate was thendissolved in caustic soda solution. An

additional 5% carbon disulfide was then added and the mass again churnedfor about one hour. The hexamethylenetetramine was added to the causticsoda solution and mixed for about /2. hour. The viscose was then allowedto ripen for about 40 hours at 18 C.

Example To a viscose solution as described, approximately 0.15% (1.07moles per kgs. of viscose) hexamethylenetetra-mine was added to andincorporated in the viscose as described above. The viscoseemployed inthe spinning of filaments had a salt test of 8.9. The viscose solutionwas extruded through a spinneret to form a 250 denier, filament yarn ata rate of about 10 meters The coagulating and regenerating bath wasmaintained at a temperature of about 56 C. and contained 7.4% sulfuricacid, 7.6% zinc sulfate and 19% sodium sulfate. The yarn was passed overa godet from which it was conducted through a hot water bath maintainedat about 90 C. During the travel through the hot water bath the yarn wasstretched approximately 90%. The yarn was then passed through a bathmaintained at about 50 C. and containing 3% sulfuric acid and 5% sodiumsulfate so as to complete the regeneration. The yarn was then collectedin a spinning .box, Washed free of acid and salts and dried.

The individual filaments have a smooth non-crenulated exterior surfaceand consist entirely of skin, no core being detectable at highmagnification. The filaments of a control yarn spun with the sameviscose but without the addition of hexamethylenetetramine and spununder the same conditions, exhibit a very irregular and crenulatedsurface and are composed of a skin portion and .a core portion with asharp line of demarcation between the skin and core.

If desired, small amounts of hexamethylenetetramine may be added to thespinning bath. Since hexamethylenetetramine is water soluble, some of itwill be leached from the filament and will be present in the bath.

Hexamethylenetetramine may be added to any desired viscose such as thosenormally used in industry, the specific viscose composition set forthabove, being merely for illustrative purposes.

The viscose may contain from about 6% to about 10% cellulose, theparticular source of the cellulose being selected for the ultimate useof the regenerated cellulose product. The caustic soda content may befrom about 4% to about 8% and the carbon disulfide content may be fromabout 30% to about 50% based upon the weight of the cellulose. Themodified viscose, that is, a viscose containing the small amount ofhexamethylenetetramine may have a salt test above about 5 and preferablyabove about 7 at the time of spinning or extrusion.

The composition of the spinning bath may be varied over a considerablerange and the presence of the hexamethylenetetramine in the viscosepermits the production of yarns having improved properties such as hightenacity, high abrasion resistance and high fatigue resistance withspinning baths having a relatively low zinc content. The

spinning bath may contain from about 5% to about 12% sulfuric acid, fromabout 15% to about 25% sodium sulfate and from about 1% to about zincsulfate.

Other metal sulfates such as iron, manganese, nickel and the like may bepresent and may replace some of the zinc sulfate. The temperature of thespinning bath may be from about 40 C. to about 75 C.

In the production of filaments for such purposes as the fabrication oftire cord, the filaments are preferably stretched after removal from theinitial coagulating and regenerating bath. From the initial spinningbath, the filaments may be passed through a hot aqueous bath which mayconsist of hot water or a dilute acid solution and may be stretched fromabout 80% to about 120%, preferably between 90% and 100%. Yarns forother textile purposes may be stretched about 20% or more. The preciseamount of stretching will be dependent upon the desired tenacity andother properties and the specific type of product being produced. It isto be understood that the invention is not restricted to the productionof filaments and yarns but is also applicable to other shaped bodiessuch as sheets, films, tubes and the like. The filaments may then bepassed through a final regenerating bath which may contain from about 1%to about 5% sulfuric acid and from about 1% to about 3% sodium sulfatewith or without small amounts of zinc sulfate.

The treatment following the final regenerating bath, or the stretchingoperation where regeneration has been completed, may consist of awashing step, the application of a finishing or plasticizing materialand drying before or after collecting, or may include other steps suchas bleaching'and the like. The treatment after regeneration will bedictated by the specific type of shaped body and the proposed usethereof.

While preferred embodiments of the invention have been disclosed, thedescription is intended to be illustrative and it is to be understoodthat changes and variations may be made without departing from thespirit and scope of the invention as defined by the appended claims.

I claim:

1. As a composition of matter, viscose containing a small amount ofhexamethylenetetramine.

2. As a composition of matter, viscose containing from about 0.1 mole toabout 20 moles of hexamethylenetetramine per 100 kgs. of viscose.

3. As a composition of matter, viscose containing from about 0.2 toabout 5 moles of hexamethylenetetramine per 100 kgs. of viscose.

4. As a composition of matter, viscose comprising from about 6% to about10% cellulose, from about 4% to about 8% sodium hydroxide, from about30% to about 50% carbon disulfide based upon the weight of the celluloseand a small amount of hexamethylenetetramine, the amount ofhexamethylenetetramine being based upon the weight of the viscose.

5. As a composition of matter, viscose comprising from about 6% to about10% cellulose, from about 4% to about 8% sodium hydroxide, from about30% to about 50% carbon disulfide based upon the weight of the celluloseand from about 0.1 mole to about 20 moles of hexamethylenetetramine per100 kgs. of the viscose.

6. As a composition of matter, viscose comprising from about 6% to about10% cellulose, from about 4% to about 8% sodium hydroxide, from about30% to about 50% carbon disulfide based upon the weight of the celluloseand from about 0.2 to about 5 moles of hexamethylenetetramine per 100kgs. of the viscose.

7. In a method of producing shaped bodies of regenerated cellulose fromviscose, the step which comprises adding to and incorporating in viscosea small amount of hexamethylenetetramine, the amount ofhexamethylenetetramine being based upon the weight of the viscose.

8. In a method of producing shaped bodies of regenerated cellulose fromviscose, the step which comprises adding to and incorporating in viscosefrom about 0.1 mole to about 20 moles of hexamethylenetetramine per 100kgs. of the viscose.

9. In a method of producing shaped bodies of regenerated cellulose fromviscose, the step which comprises adding to and incorporating in viscosefrom about 0.2 to about 5 moles of hexamethylenetetramine per 100 kgs.of the viscose.

10. The method of producing shaped bodies of regenerated celluloseconsisting entirely of skin which comprises spinning viscose containinga small amounuof hexamethylenetetramine into an aqueous acidicSPll'lIllIlg bath containing zinc sulfate, the amout ofhexamethylenetetramine being based upon the weight of the viscose.

11. The method of producing shaped bodies of regenerated celluloseconsisting entirely of skin which cornprises spinning viscose containingfrom about 0.1 mole to about 20 moles of hexamethylenetetramine per 100kgs. of viscose into an aqueous acidic spinning bath containing fromabout 1% to about 10% Zll'lC sulfate.

12. The method of producing shaped bodies of regenerated celluloseconsisting entirely of skin WhlCh comprises spinning viscose containingfrom about 0.2 to about 5. moles of hexamethylenetetramine per 100 kgs.of VIS- cose into an aqueous acidic spinning bath containing from about1% to about 10% zinc sulfate.

13. The method of producing shaped bodies of regenerated celluloseconsisting entirely of skin which comprises spinning viscose containinga small amount of hexa- .methylenetetramine into an aqueous acidlcspinnmg bath containing from about 1% to about 10% zinc sulfate andstretching the body at least 20%, the amount of hexamethylenetetraminein the viscose being based upon the weight of the viscose.

14. The method of producing shaped bodies of regenerated celluloseconsisting entirely of skin which comprises spinning viscose containinga small amount of hexamethylenetetramine into an aqueous acidic spinningbath containing from about 1% to about 10% zinc sulfate and stretchingthe body between about and about 120%, the amount ofhexamethylenetetramine in the viscase being based upon the weight of theviscose.

15. The method of producing shaped bodies of regenerated celluloseconsisting entirely of skin which comprises spinning viscose containingfrom about 0.1 mole to about 20 moles of hexamethylenetetramine per kgs.of viscose into an aqueous acidic spinning bath containing from about 1%to about 10% zinc sulfate and stretching the body between about 80% andabout 16. The method of producing shaped bodies of regen- "eratedcellulose consisting entirely of skin which com- 5 prises spinningviscose containing from about 0.2 to about 5 moles ofhexamethylenetetrarnine per 100 kgs. of viscose into an aqueous acidicspinning hath containing from about 1% to about 10% zinc sulfate andstretching the body between about 86% and about 120%.

17. The method of producing shaped bodies of regenerated celluloseconsisting entirely of skin which comprises spinning viscose containinga small amount of hexamethylenetetramine, the amount ofhexarnethylenetetramine being based upon the Weight of the viscose, intoan aqueous acidic spinning bath containing sulfuric acid and from abouti% to about 19% zinc sulfate, removing the body from the spinning hathbefore regeneration of the cellulose has been completed, stretching thepartially regenerated cellulose body at least 20% and completing 5 theregeneration of the cellulose.

2,535,044 Cox Dec. 26, 1950

10. THE METHOD OF PRODUCING SHAPED BODIES OF REGENERATED CELLULOSECONSISTING ENTIRELY OF SKIN WHICH COMPRISES SPINNING VISCOSE CONTAININGA SMALL AMOUNT OF HEXAMETHYLENETETRAMINE INTO AN AQUEOUS ACIDIC SPINNINGBATH CONTAINING ZINC SULFATE, THE AMOUNT OF HEXAMETHYLENETETRAMINE BEINGBASED UPON THE WEIGHT OF THE VISCOSE.